What is Orginal Sin?

[tackattack]

I'd like to hear from Christians what Original Sin is? Because I can never understand why God would allow the sin of a father(Adam) to be committed to the son(Humanity). I've heard reasons from others to believe why this is wrong but can anyone prove why it is right?

Well if the hecklers can calm down for a bit I don't mind having a real discussion about it, as I haven't shared much about it in the forum to date.

Definition:
Original Sin- When the average Presbyterian/Calvinist says it without thinking they usually mean the sin that Adam and Eve committed in the Garden of Eden. If you ask a catholic they quote their encyclopedia

(1) the sin that Adam committed; (2) a consequence of this first sin, the hereditary stain with which we are born on account of our origin or descent from Adam.

If you ask a protestant apologist, Calvinist or Christian theologian (I've asked) it a little different of a definition. I (as the latter group) define "original sin" as this: original sin would be better stated as "originating sin". It would be the quality (or nature) fundamental to mankind's nature that causes him to transgress the will of God. This sin of nature is original because we are all born with it. It is also total in that it is irreparable by his own power completely. It does not limit or remove free-agency. It was an intentional design that we have the opportunity and availability of everything possible for learning moral right by God’s standard, however our lack of trust and a compulsive self-reliance put us culpable individually for our actions. It is not an inherited sin in that if you did everything right you would be guilty regardless, just a statement of nature that it’s unfathomable to do right 100% of the time when learning what is and is not acceptable to an objective moral standard.

I hope that clarifies my position and answers the question a bit. Fire away.